1. Field of the Invention
This invention relates in general to stapling apparatus, and more particularly, to a stapling apparatus that includes a stapler head having a staple-material path defining cover.
Electrostatographic copiers and printers for example are well known for producing a series of pre-collated image-bearing sheets which can then be compiled by an attached finisher portion thereto into a stack for binding together. As disclosed in commonly assigned U.S. Pat. No. 4,318,555 issued Mar. 9, 1982 in the name of Adamski et al, the use of a stapling system or apparatus to effect such binding is well known.
Typically, such a stapling apparatus utilizes either preformed staples, or a continuous supply of staple material, such as staple wire, from which a desired length thereof can then be cut for forming into a staple. Generally, for stapling copy sheets in copiers and printers, a stapling apparatus utilizing a continuous supply of staple material is preferred because it can be more versatile, more economical, and more efficient than a similar apparatus utilizing preformed staples.
Unfortunately however, in stapling apparatus which utilize a continuous supply of staple material such as staple wire, such staple material may vary in strength from relatively soft to relatively hard and springy, depending on the work piece to be stapled. For hard springy staple material or wire, conventional stapling apparatus as disclosed, for example, in U.S. Pat. Nos. 4,369,908 and 4,318,555 typically employ thick heavy-duty internal members in the stapler head for shearing such material, as well as for forming and driving staples therefrom. Such thick, heavy-duty internal members undesirably take up, as well as, require a lot of room for movement within the stapler head. As a consequence of such room taken up by the internal members, the spacing between the cover and base of the stapler head is usually many times greater than the thickness or diameter of the staple material. Reverse radius curvatures, recesses or grooves therefore have to be machined at the tips of such internal members in order to help define a staple-material path within the stapler head. Such machining is of course expensive, but more importantly, there can be misalignment between the machined grooves or recesses, and other fixed portions of a staple-material path in the stapler head.
In addition, hard and springy staple material is usually supplied coiled or wound about a spool from which it can then be removed peacemeal by pulling on a leading end thereof. Normally, depending on the hardness or springiness of the staple material, variations in the sizes of different spools, and variations in the amount and diameter of the winding, unfortunately tend to undesirably create semi-permanent curls in the staple material. Such curls in the staple material are undesirable because they tend to cause jams and misfeeds within the stapler head for example, particularly where there may be misalignment in the staple-material path therein.
Conventional stapling apparatus which include thick heavy-duty internal members as described above therefore must employ a staple material straightener that attempts to reverse, and hence to remove the curl therein. Alternatively, the size of staple material spools, and the amounts of staple material windings thereon must be carefully restricted in order to minimize variations in such curls, and hence to minimize the likelihood of the jams and misfeeds they cause. It has been found that the use of thick heavy-duty staple forming and driving members, with hard springy staple wire, imposes severe and costly restrictions on such a stapling apparatus, as well as, that despite such restrictions misfeeds and jams still occur.